The development of new catalytic methods for stereocontrolled synthesis of bioactive compounds is an important goal of modern organic chemistry. The aim of the proposed research is to apply chiral thiourea- based catalysts to the development of new methods for the enantioselective synthesis of nitrogen-containing heterocycles. Specifically, this research seeks to extend the scope of the anion binding mode of thiourea catalysis, which has been applied in highly enantioselective arene-N-acyliminium ion cyclization reactions, to enantioselective cyclizations of non-aromatic @-nucleophiles onto prochiral N-acyliminium ions. New chiral thiourea catalysts will be prepared and examined in the context of several alternate modes of cyclization involving allyl- and vinylsilane nucleophiles. Because nitrogen-containing heterocycles are structural features of many natural and synthetic bioactive compounds with therapeutic properties, it is anticipated that the proposed research will provide chemists with useful new tools for the preparation of bioactive compounds and find applications in drug discovery and development. PUBLIC HEALTH RELEVANCE: The purpose of the proposed research is to apply thiourea-based catalysts to the development of new enantioselective methods for the synthesis of nitrogen-containing ring systems. As nitrogen-containing ring systems are commonly found in bioactive compounds, it is anticipated that the proposed research will ultimately provide chemists with new tools for the stereoselective synthesis of bioactive compounds and find applications in drug discovery and development.